Liquid supply system, liquid processing apparatus, and liquid supply method

Abstract

A liquid supply system includes: a tank that stores a processing liquid; a circulation line that returns the processing liquid sent from the tank, to the tank; a pump that forms a circulation flow of the processing liquid in the circulation line; a filter provided on a downstream side of the pump in the circulation line; a back pressure valve provided on a downstream side of the filter in the circulation line; and a controller that controls each unit. When stopping an operation of the pump, the controller controls the pump and the back pressure valve such that a differential pressure between an upstream side and a downstream side of the filter becomes equal to or less than a predetermined threshold value, during a period from when a discharge pressure of the pump starts to decrease until the operation of the pump is stopped.

1 . A liquid supply system comprising:
 a tank configured to store a processing liquid;   a circulation line configured to return the processing liquid sent from the tank, to the tank;   a pump configured to form a circulation flow of the processing liquid in the circulation line;   a primary filter provided on a downstream side of the pump in the circulation line;   a back pressure valve provided on a downstream side of the primary filter in the circulation line; and   a controller configured to control each unit,   wherein when stopping an operation of the pump, the controller controls the pump and the back pressure valve such that a differential pressure between an upstream side and a downstream side of the primary filter becomes equal to or less than a predetermined threshold value, during a period from when a discharge pressure of the pump starts to decrease until the operation of the pump is stopped.   
     
     
         2 . The liquid supply system according to  claim 1 , wherein the controller controls the differential pressure between the upstream side and the downstream side of the filter to be equal to or less than the predetermined threshold value by lowering the discharge pressure of the pump and increasing a valve opening degree of the back pressure valve. 
     
     
         3 . The liquid supply system according to  claim 1 , wherein when stopping the operation of the pump, the controller controls the pump and the back pressure valve such that the differential pressure between the upstream side and the downstream side of the primary filter becomes equal to or less than a maximum differential pressure between the upstream side and the downstream side of the filter when the circulation flow of the processing liquid is formed in the circulation line. 
     
     
         4 . The liquid supply system according to  claim 1 , further comprising:
 a first pressure sensor provided on the upstream side of the primary filter; and   a second pressure sensor provided on the downstream side of the primary filter,   wherein the controller calculates a maximum differential pressure between the first pressure sensor and the second pressure sensor when the circulation flow of the processing liquid is formed in the circulation line, and   when stopping the operation of the pump, the controller controls the pump and the back pressure valve such that the differential pressure between the upstream side and the downstream side of the primary filter becomes equal to or less than the maximum differential pressure.   
     
     
         5 . The liquid supply system according to  claim 1 , wherein when starting circulation of the processing liquid in the circulation line, the controller controls the pump and the back pressure valve such that the differential pressure between the upstream side and the downstream side of the primary filter becomes equal to or less than a maximum differential pressure between the upstream side and the downstream side of the primary filter when the circulation flow of the processing liquid is formed in the circulation line. 
     
     
         6 . The liquid supply system according to  claim 1 , further comprising:
 a heater provided between the pump and the primary filter in the circulation line; and   a branch circulation line branching off between the heater and the primary filter in the circulation line, and returns the processing liquid sent from the tank, to the tank,   wherein before starting circulation of the processing liquid in the circulation line, the controller heats the processing liquid with the heater while operating the pump to circulate the processing liquid through the branch circulation line.   
     
     
         7 . The liquid supply system according to  claim 6 , further comprising:
 a junction on the downstream side of the primary filter in the circulation line, from which a supply line for supplying the processing liquid to a substrate processing section diverges;   a valve provided between the primary filter and the junction; and   a drain line connected between the primary filter and the valve in the circulation line,   wherein before starting the circulation of the processing liquid in the circulation line, the controller closes the valve and heats the processing liquid with the heater while circulating through the branch circulation line, and then drains the processing liquid from the drain line after heating with the heater.   
     
     
         8 . The liquid supply system according to  claim 7 , wherein before starting the circulation of the processing liquid in the circulation line, the controller repeats circulating in the branch circulation line and draining from the drain line. 
     
     
         9 . The liquid supply system according to  claim 7 , further comprising:
 a flowmeter provided between the primary filter and the valve,   wherein the drain line is connected to a downstream side of the flowmeter in the circulation line, and   the controller monitors a drainage amount of the processing liquid drained from the drain line, by the flowmeter.   
     
     
         10 . The liquid supply system according to  claim 9 , wherein when the drainage amount has reached a predetermined amount, the controller opens the valve to allow the processing liquid to flow through the circulation line, thereby forming the circulation flow. 
     
     
         11 . The liquid supply system according to  claim 6 , wherein the controller circulates the processing liquid in the branch circulation line while circulating the processing liquid in the circulation line. 
     
     
         12 . The liquid supply system according to  claim 11 , further comprising:
 a flow rate adjustor provided in the branch circulation line, and configured to adjust a flow rate of the processing liquid flowing through the branch circulation line,   wherein when the processing liquid is circulated through the circulation line, the controller circulates the processing liquid through the branch circulation line at a flow rate smaller than before the circulation of the processing liquid in the circulation line is started.   
     
     
         13 . The liquid supply system according to  claim 7 , further comprising:
 a recovery tank configured to collect the processing liquid flowing through the drain line;   a recovery filter configured to filter the processing liquid collected in the recovery tank; and   a return line configured to connect the recovery filter and the tank to each other, and return the processing liquid filtered by the recovery filter to the tank.   
     
     
         14 . The liquid supply system according to  claim 1 , further comprising:
 a junction on the downstream side of the primary filter in the circulation line, from which a supply line for supplying the processing liquid to a substrate processing section diverges;   a valve provided between the primary filter and the junction; and   a drain line connected between the primary filter and the valve in the circulation line,   wherein before starting circulation of the processing liquid in the circulation line, the controller closes the valve and drains the processing liquid from the drain line.   
     
     
         15 . A liquid supply system comprising:
 a tank configured to store a processing liquid;   a circulation line configured to return the processing liquid sent from the tank, to the tank;   a pump configured to form a circulation flow of the processing liquid in the circulation line;   a filter provided on a downstream side of the pump in the circulation line;   a back pressure valve provided on a downstream side of the filter in the circulation line; and   a controller configured to control each unit,   wherein when stopping an operation of the pump, the controller controls the pump and the back pressure valve such that a flow rate of the processing liquid flowing through the circulation line becomes equal to or less than a predetermined threshold value, during a period from when a discharge pressure of the pump starts to decrease until the operation of the pump is stopped.   
     
     
         16 . A liquid processing apparatus comprising:
 a liquid processing section configured to process a substrate with the processing liquid; and   a supply line configured to supply the processing liquid to the liquid processing section from the liquid supply system according to  claim 1 .   
     
     
         17 . A liquid supply method comprising:
 operating a pump, thereby forming a circulation flow of a processing liquid in a circulation line that returns the processing liquid sent from a tank, to the tank;   shutting down the circulation flow of the processing liquid in the circulation line; and   starting up the circulation flow of the processing liquid in the circulation line,   wherein in the shutting down of the circulation flow, when stopping an operation of the pump, the pump and a back pressure valve are controlled such that a differential pressure between an upstream side and a downstream side of a filter becomes equal to or less than a predetermined threshold value, during a period from when a discharge pressure of the pump starts to decrease until the operation of the pump is stopped, the back pressure valve being provided on the downstream side of the filter in the circulation line, and the filter being provided on a downstream side of the pump in the circulation line.   
     
     
         18 . The liquid supply method according to  claim 17 , wherein in the shutting down of the circulation flow, when stopping the operation of the pump, the pump and the back pressure valve are controlled such that the differential pressure between the upstream side and the downstream side of the filter becomes equal to or less than a maximum differential pressure between the upstream side and the downstream side of the filter during the forming of the circulation flow. 
     
     
         19 . The liquid supply method according to  claim 17 , wherein in the starting up of the circulation flow, when circulation of the processing liquid in the circulation line is started, the pump and the back pressure valve are controlled such that the differential pressure between the upstream side and the downstream side of the filter becomes equal to or less than a maximum differential pressure between the upstream side and the downstream side of the filter during the forming of the circulation flow.